Device for extending and folding back masts or towers applicable to cranes and the like



June 18, 1968 P. DURAND 3,338,310

DEVICE FOR EXTENDING AND FOLDING BACK MASTS OR TOWERS APPLICABLE TO CRANES AND THE LIKE Filed Feb. 20, 1967 2 Sheets-Sheet 1 June 18, 1968 P. DURAND 3,388,810

DEVICE FOR EXTENDING AND FOLDING BACK MASTS OR 7 TOWERS APPLICABLE TO CRANES AND THE LIKE Filed Feb. 20, .1967 2 Sheets-Sheet 2 United States Patent 3,388,810 DEVICE FOR EXTENDING AND FOLDING BACK MASTS 0R TOWERS APPLICABLE TO CRANES AND THE LIKE Pierre Durand, Lyon, Rhone, France, assignor to Richier, Paris, France, a company of France Filed Feb. 20, 1967, Ser. No. 617,266 Claims priority, applicsation France, Feb. 24, 1966,

3 Claims. 3:1. 212-46) ABSTRACT OF THE DISCLOSURE A hoisting appliance having an erectable mast transported reclining on a platform and made of two telescoped sections, one of which has one of its sides pivotally connected to the platform about a horizontal axis, while the other has its opposite side pivotally connected to the end of a link member hingedly connected to the platform, whereby bodily pivoting the telescoped sections about the hinge axis of the first section on the platform causes translation of the two sections relatively to each other.

Background of the invention Summary of the invention In accordance with this invention, the mast or jib consists of two telescoped sections, of which one has one side pivotally connected to the erecting platform about a horizontal axis, while the other has its side remote from the aforementioned side pivotally connected to the end of a link member hingedly connected to the platform about a horizontal axis, whereby a motion of the two telescoped sections relatively to each other, resulting from a force exerted between the two sections, will, depending on the direction in which the force is exerted, cause either the folded reclining mast to be moved into the vertical extended position, or conversely the vertically extended mast to be moved into its retracted horizontal position.

Brief description of the drawing FIGURES 1, 2 and 3 are side elevation views of an embodiment of the invention as applied to a building crane, showing three different operative positions thereof;

FIGURE 4 shows an embodiment of control means utilizing a central jack, and

FIGURE 5 shows an alternative form of embodiment.

Description of the preferred embodiments Reference to the drawing shows a building crane the mast of which comprises a base 1 attached to a platform 2, on which said base is either reclining for transport as shown in FIGURE 1, or erected in the vertical position for operation of the crane as shown in FIGURE 3. Platform 2 is fitted with wheels 3 to enable it to be moved, and also with bracing means (not shown) such as jack means to immobilize it on a chosen location.

The base 1 is made up of two sections 4 and 5 placed one within the other and devised for mutual telescoping movement. By way of example, guide wheels (not shown) could be carried by the inner section 5 and roll on guideways on the outer section 4. In the example shown in the drawing, the sections 4 and 5 are assumed to be of square or rectangular cross-section but could obviously have any convenient cross-sectional shape.

Sections 4 and 5 are further assumed to be lattice sections, as is customary in crane mast on jib construction.

Inner section 5 is pivotally connected to platform 2 about a horizontal axis b along that of its edges perpendicular to the longitudinal axis of platform 2 which is applied against the latter when the base is reclining (FIG- URE 1), while outer section 4 has its opposite side pivotally connected about an axis 7 to the end of two links 8 positioned symmetrically with respect to the longitudinal centerline of platform 2. These links, which merge together on the drawing (but which could be replaced by a frame) are hingedly connected to platform 2 about a horizontal axis 9. The hinge axes 6 and 9 on platform 2 are sufficiently spaced for inner mast section 5 to be able to come to bear against the platform between these axes when it is in the erected position shown in FIGURE 3.

A force generating mechanism such as a hydraulic jack, screw jack, reeving system, rack device, or the like, acting on one hand against outer section 4 and on the other against inner section 5, enables opposed forces to be exerted thereagainst which are effective in moving the mast either from its reclining position shown in FIGURE 1 to its vertical position shown in FIGURE 3, or vice versa.

This. mechanism, a specific form of embodiment of which will be described hereinafter, may be positioned in the interval between sections 4 and 5, or centrally, or entirely external to sections 4 and 5, its location being such that the direction of the force it exerts passes above axis 6 whereby to produce a rotating moment thereabout.

The principle of operation of the device hereinbefore described will be readily understood.

If, starting from the position in FIGURE 1, the force generating mechanism is activated so that the force it exerts on outer section 4 is directed along arrow f, with the reaction taking place against section 5, then the moment which is generated as mentioned above on section 4 hinged about axis 6 will initiate pivotal motion of the assembly about axis 6 and a reaction of links 8 against telescoped section 4. The hinge points 7 of links 8 on section 4- then describe circular arcs having their centre at 9, whereby section 4 is pulled along inner section 5 and telescopes over the same, with the overall result that the mast gradually pivots about axis 6 and at the same time extends itself. In so doing it moves from the position in FIGURE 1 to the position in FIGURE 2, and ultimately to that in FIGURE 3. Obviously, this motion tends to be self-sustaining as soon as the centre of gravity of the mast moves past the vertical plane through axis 6. For this reason it is preferable for the force generating mechanism connected between sections 4 and 5 to be of the positive type, i.e. a jack or rack mechanism rather than a reeving system, in order to avoid uncontrolled terminal motion and ensuing shock loadings as the inner section 5 of the mast base contacts platform 2.

As FIGURE 1 clearly shows, outer telescoping section 4 is formed with a bevelled end 10 which is pivotally connected to the links 8. As the figure shows, this ensures that this end is always located above and behind hinge axis 6 and does not therefore hinder initiation of the pivotal motion; further the hinge points 7 are located above and between axes 6 and 9, which is preferable for eificient operation.

Obviously, locking means may be provided in order to unite sections 4 and 5 after the mast has been erected into the position in FIGURE 3.

In order to retract the mast and fetch it into its reclining position on the platform, the force generating mechanism is activated so as to produce forces acting in opposite directions between sections 4 and 5 after the locking means therebetween have been released.

The drawing shows a counterweight 11 positioned on the platform on that side of the hinge-axes remote from the mast, in order to balance the weight of same.

FIGURE 4 shows a preferred embodiment of the force generating mechanism for producing mutual telescoping of the two mast sections. This mechanism includes a hydraulic jack of which one part, the cylinder 12 for example, is fixedly mounted axially at the outer end of outer section 4, for instance on a frame 13 rigid with section 4. The rod 16 of jack 12 has its free end pivotally connected to a cross-member 17 adapted to bear against and lock onto the end of inner mast section 5a.

Initially the jack is not under pressure and retracted, in the position shown in FIGURE 1. When the jack is set under pressure, the force it exerts on outer mast section 4 in the direction of arrow f, as it reacts against crossmember 17, inner section 5 and hinge point 6, causes erection of the mast into the vertical position, as explained precedingly. In the illustrated example, the head of outer section 4 housing jack 12 forms a pivot 14 on which is rotatable a crane jib support 15, as is common practice in the crane building art. The jib, not shown, may be folded along base 4 when same is in its stowed transport position and can be moved into its operative position after the mast has been erected by means of suitable reeving means, well-known per se, which call for no description since they fall outside the scope of the present invention.

It goes without saying that the specific forms of embodiment described hereinabove are intended for exernplary purpose only and that changes and substitutions could be made therein without departing from the scope of the invention.

By way of example, FIGURE 5 shows an alternative embodiment in which mast section 4, which is pivotally connected to rods 8, is the inner instead of the outer section, the outer mast section being accordingly hingedly connected to the platform as at 6. FIGURE 5 also shows an alternative way of devising the force generating mechanism between the two telescoping sections, which mechanism consists in this case of a gearwheel 20 carried on i one of the mast sections and meshingwith a rack 21 car ried on the other section, gearwheel 20 being driven by a suitable motor (not shown).

In yet another alternative constructional form, the mast could be extended by means of a mechanism external thereto, such as a winch 22 pulling a rope 23 fastened to outer section 4 and running over an intermediate pulley 24.

I claim:

1. In a hoisting appliance having a mast transportable in a reclining position on a platform, the combination comprising two mutually telescoping sections forming part of said mast, an articulation about a horizontal axis be tween one side of one of said telescoping sections and the platform, linkage means with two hinge points about horizontal axes parallel to said horizontal axis, one of said hinge points connecting said linkage means to the other telescoping section on a side thereof remote from that side of the first mentioned section which is articulated on said platform and the other hinge point interconnecting said linkage means with said platform in spaced relationship with the articulation point of said first section, said first mentioned hinge point, in the reclining position of said mast, lying above and between the hinged connection point of said linkage means to said platform and the hinged connection point of the other telescoping section to said platform, whereby bodily pivotal motion of said two telescoping sections about said articulation is accompanied by a translation motion of said two sections relatively to each other.

2. A hoisting appliance as claimed in claim 1, wherein the telescoping section hingedly connected to said linkage means comprises a projecting portion carrying the hinged connection point to said linkage means.

3. A hoisting appliance as claimed in claim 2, wherein the telescoping section hingedly connected to said linkage means has its base disposed obliquely.

References Cited UNITED STATES PATENTS ANDRES H. NIELSEN, Primary Examiner. 

